Purpose
Microbes play a key role in soil nutrient cycling and supply in the extensive semiarid grassland ecosystem, where no fertilizers are applied. However, the role of fungi vs bacteria in nitrogen (N) mineralization in such ecosystem is poorly understood. The objective of this study was to determine the impacts of different mowing practices on fungal and bacterial communities and the relationships between the two microbial communities and net N mineralization rate (Rm).
Materials and methods
This study was based on a 13-year mowing experiment in Inner Mongolia. The treatments included mowing once every second year (M1/2), mowing twice every 3 years (M2/3), mowing once a year (M1), mowing twice a year (M2), and the unmown (control, CK). Soil basic chemical properties, Rm, microbial biomass, bacterial and fungal community abundance, and diversity were determined, and fungal phylogeny and the relationship between microbial community and Rm were analyzed.
Results and discussion
Moderate mowing (M1/2, M2/3, and M1) enhanced soil carbon and nitrogen stocks, Rm, fungal community abundance and diversity which might mainly because of the increased decomposer fungi species, but the higher frequency mowing (M2) significantly decreased the above. There was a significant correlation between fungal community abundance and Rm (r = 0.688, P = 0.005) in this study. However, different mowing practices had little effect on the bacterial community, which might due to human disturbance (mowing practices) and poor environmental conditions (drought, limited available nitrogen and phosphorus).
Conclusions
Overall, fungi may play a more important role than bacteria in N mineralization under mowing management in such a grassland ecosystem. Moderate-frequency mowing, e.g., M1, is more appropriate for maintaining soil microbial communities and soil fertility, whereas the high-frequency mowing, e.g., M2, is not sustainable for maintaining soil nutrients and microbial community in such a semiarid grassland ecosystem in a long term.